Anatomy of Inguinal canal in a nutshell

Anatomy of Inguinal canal

1. An oblique intermuscular passage through the inferior portion of the anterior abdominal wall.
2. During development, it serves as a route of passage for the testes from the posterior abdominal wall to the scrotum.
3. Contains the spermatic cord in males and the round ligament in females.
4. 4-5 cm in length.
5. Orientation:
   • Runs parallel / superior to the inguinal ligament along the medial ½ of the ligament.
   • Runs from deep (lateral) to superficial (medial).
   • Extends from the deep inguinal ring (lateral) to the superficial inguinal ring (medial).

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1 – spina iliaca anterior superior; 2 – arcus iliopectineus; 3 – fascia lata (отрезана); 4 – lig. inguinale; 5 – anulus femoralis; 6 – lig. lacunare; 7 – anulus inguinalis superficial; 8 – crus mediale; 9 – crus laterale; 10 – tuberculum pubicum; 11 – funiculus spermaticus; 12 – m. pecti-neus (отрезан); 13 – m. cremaster; 14 – ramus inferior ossis pubis; 15 – foramen obturatum; 16 – corpus ossis ischii; 17 – acetabulum; 18 – v. femoralis; 19 – n. femoralis; 20 – a. femoralis; 21 – m. iliopsoas; 22 – lacuna musculorum

Testis Descent

1. are attached to the Gubernaculum of testis (equivalent to the Gubernaculum of ovary in females) which direct its migration through the abdominal wall.
   1. As it is pulled → pulls the peritoneum with it → creates the processus vaginalis.
   2. When it enters the scrotum: has a portion of transversalis fascia, external oblique, internal oblique, but NOT the transverse abdominus.
   3. Gubernaculum ends up anchoring testes to cutaneous tissue in scrotum.
   4. Spermatic cord: made up of fascia and muscles that were taken along with testes during migration.
2. The ductus deferens and testicular artery/vein travel through the deep inguinal ring.
3. Fibers of external oblique that form boundary of superficial inguinal ring: Medial crus, lateral crus, and between them have small fibers = intercrural fibers between them (hard to see).

Walls of inguinal canal

1. Anterior wall: aponeurosis of external oblique muscle
2. Posterior wall: tranversalis fascia, Medially reinforced by conjoined tendon
3. Floor: inguinal ligament, lacunar ligament
   • Inguinal ligament forms trough in which spermatic cord sits.
4. Roof: arching fibers of the internal oblique and transverses abdoiminus

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1 – inguinal ligament; 2 – spermatic cord; 3 – external oblique aponeurosis;  4 – site of dissection of the external oblique aponeurosis; 5 – internal oblique; 6 – internal oblique aponeurosis; 7 – transverse abdominis; 8 – transverse fascia; 9 – conjoined tendon; 10 – iliopubic tract.

Inguinal canal in female

1. Round ligament travels through the canal
   • Fibers spread out into labia majora connective tissue.
   • The ligament attaches to the lateral wall of the uterus → then continues as the ovarian ligament attaches the ovary to the uterus.
2. The diameter of the canal is much narrower in females, thus they are less likely to have inguinal hernias.

Inguinal canal in male

• Spermatic cord

1. 1. Contents:
      • ductus deferens → continues into epididymis
      • testicular artery, Vas artery
      • pampiniform plexus = meshwork of veins that wrap around ductus deferens and testicular artery.
      • lymph vessels
      • nerves = both sympathetic/parasympathetic to testes.

1. 1. Layers:
      1. external spermatic fascia = continuous with external oblique muscle
      2. cremasteric fascia (muscular layer) = continuous with internal oblique.
      3. internal spermatic fascia = from transversalis fascia.

• Testes

1. 1. Saccus vaginalis: forms cavity around the anterior surface of testes.
      •  Has pockets of serrous lined membrane that once extended from peritoneum.
      • Inflammation of this causes fluid build up
      • Hydrocele = excess fluid in a persistent process vaginalis.  Occurs somewhere along the cord or at the testis.
   2. Layers:
      • Parietal layer of tunica vaginalis = lines the internal spermatic fascia.
      • Covering the testes = visceral layer of tunica vaginalis.
      • Thicker CT layer = tunica albuginea, beneath visceral layer.
      • Deep to the tunica albuginea = lobules of the seminiferous tubules.
   3. Blood/nerve/lymph supply to testes: all related to the embryology of testes.
      • Testes originated along the abdominal wall, and those supplies are maintained.  These suppliers travel back along with vas deferens.
      • Abdominal aorta → gives testicular artery.
      • Venus blood goes back to renal vein / inferior vena cava.
   4. Nerve supply: sympathetic from lumbar region trunk.  Vagus nerve supplies parasympathetics.
   5. Lymph: important in testicular cancer.  Drains to lymph nodes along aorta in posterior abdominal wall.  Thus, cancer may spread to abdominal lymph nodes.  Scrotum drains to inguinal lymph nodes.

Inguinal hernias

• Hernia = abnormal protrusion of a structure from the cavity in which it belongs.
• Inguinal hernia = abdominal hernia through anterior abdominal wall in the inguinal region.
• Types of Inguinal hernias:
  • Direct: leaves the abdominal cavity medial to the inferior epigastric artery within the inguinal triangle.

1. 1. 1. travels anteriorly through the posterior wall of the inguinal canal that is formed by the transversalis fascia and exits via the superficial inguinal ring, hence only the medial portion of the inguinal canal is traveled.
      2. Covered by one or two layers of the spermatic cord
      3. Transversalis fascia forms the hernial sac.
      4. Less common than indirect hernia, usually occurs in men older than 40.

1. • Indirect: leaves the abdominal cavity lateral to the inferior epigastric artery.

1. 1. 1. travels through the deep inguinal ring, the entire inguinal canal, and the superficial inguinal ring.
      2. Originates lateral to the inferior epigastric vessels.
      3. Is covered by all 3 layers of the spermatic cord.
      4. Remains of the process vaginalis forms the hernial sac.
      5. 20 times more common in males than females.
      6. AKA congenital hernias, occur in young boys. Persistent process vaginalis is a cause.  A loop of small intestine may be pushed into the parietal peritoneum invagination remaining following testicular migration.

• • Retractable hernia: only have herniation when have pressure on abdominal wall.
• Hernia creates a problem when mass of intestine extends too far for blood supply to remain competent.  When it is compromised, have strangulated hernia = edema, inflammation, damage to intestine → may lead to eventual sepsis.

Internal surface of anterior abdominal wall

• Inguinal triangles of Hesselbach: on either side of rectus abdominus
  • Boundaries:

• • 1. medial border = rectus abdominus
    2. lateral border = inferior epigastric vessels
    3. inferior border = inguinal ligament
  • This triangle is directly behind the superficial inguinal ring.
  • This is a weak spot.
• The deep ring is where the ductus deferens travels.
• Inguinal ligament → continues as iliopubic tract

Also read:

1. The Inguinal Canal @ TeachMeAnatomy
2. Practice Anatomy tests for free!
3. Best Anatomy books for Medical students
4. Best Anatomy websites & journals
5. Anatomy syllabus in (CBME) in India
6. Anatomy syllabus in Russia & Other CIS
7. Anatomy syllabus in China

Also Watch:

• Inguinal Region & Canal @ Lecturio